Impossible according to who? You really need to cut out on making generalizations. The parents of a friend started dating in June and got married in August on the same year. That was 40 years ago and they are still together.
Sometimes, people just meet the right one and they just click regardless of the time frame. There's nothing impossible about that.
It is impossible and the notion that people are suggesting otherwise is just utterly absurd.
You need to know someone before you can judge whether they are marriage material and you cannot do that in such a short time frame.